resistance to slag penetration
resistance to CO attack
RUL
permanent linear change
✅ The correct answer is option A.
Engineering
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3042. Thermal spalling mainly occurs during __________ of furnaces.
cooling down
warming up
both (a) & (b)
neither (a) nor (b)
✅ The correct answer is option C.
3043. To resist spalling tendency, a refractory should have
greater diffusivity.
low specific heat.
low thermal co-efficient of expansion.
all (a), (b) and (c).
✅ The correct answer is option D.
3044. In panel test for spalling resistance, the average face temperature of panel assembly is maintained at __________ °C for 24 hours.
700
1000
1600
2000
✅ The correct answer is option C.
3045. Capacity of a refractory brick to withstand-sudden changes in temperature is denoted by the property called
spalling resistance.
refractoriness.
refractoriness under load (RUL).
none of these.
✅ The correct answer is option A.
3046. Because of its very high refractoriness of the order of __________ °C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns.
1800
2200
2400
2700
✅ The correct answer is option D.
3047. __________ is the measure of the strength of refractory under the combined effect of temperature & load.
Porosity
RUL
Specific gravity
Thermal conductivity
✅ The correct answer is option B.
3048. Test piece for determination of RUL of a refractory is heated in a/an
oxidising atmosphere
reducing atmosphere
electric furnace
neutral atmosphere
✅ The correct answer is option C.
3049. Walls, roofs & combustion chambers of annealing furnaces are made of __________ bricks.
high duty fireclay
silica
mullite
carborundum
✅ The correct answer is option A.
3050. Silica refractories are not used in
coke oven walls.
beehive coke ovens.
dome and upper portion of B.F. stoves.
open hearth furnace roof.
✅ The correct answer is option B.